This isn't finished. But it will be. Two residential towers, dense with trees, will have their official opening later this year in downtown Milan, Italy, near the Porta Garibaldi railroad station. (The image is not a photograph, but an architect's rendering. The towers are built and the trees are going in right now.) I love this. I think these towers are gorgeous. Milan is a very polluted town; these trees will cleanse the air, pumping out oxygen and greening the cityscape. I think cities one day could look like mountain vistas; I'm enthralled.

But I am not Tim De Chant, tree lover, blogger, critic, who says this won't work. All these trees, he thinks, are about to be dead. He recently posted an essay on his Per Square Mile blog, aimed at architects. He called it, "Can we please stop drawing trees on top of skyscrapers?" He thinks builders know squat about trees. I hope he's wrong.

The Milan project, called Bosco Verticale (or Vertical Forest), took years to plan. The architects say they consulted with botanists, chose plants that could handle the height, the windy exposures, the Milanese summer heat and winter cold. The plants they selected were then "precultivated" (Genetically enhanced? They don't say.) to acclimate to their new high rise digs. There will be lots of them: 480 big and medium sized trees, 250 small trees, 11,000 cover plants and 5,000 shrubs. If they weren't stacked vertically, they'd occupy 2.5 acres of forest.

Tim, to be fair, is worried about trees on skyscrapers. These two towers, one 260 feet tall, the other 367, are tall, but not crazy tall. So maybe there's a chance they'll make it. Reading Tim's essay, though, makes me wonder.

Beware The Wind!

Wind, he writes, is a "formidable force" at higher elevations. "Ever seen trees on the top of a mountain? Their trunks bow away from the prevailing winds." The trees in the architects' drawings are "tall and graceful." Not a good sign. Also, he says trees in high places often have differently textured leaves, "by including tiny hairs ... which expand each leaf's surface area." Did the architects know about this? I hope so.

Beware The Winter! The Summer! The Lazy Gardener!

"Next let's add extreme heat and cold to the mix," he writes. "Extreme cold, well, we all know what that does. It can kill a plant, turning the water inside its cells into lethal, crystalline knives." Higher off the ground, when the wind is up, the cold may be too cruel to these plants. Not to mention, "How are these trees going to be watered and fertilized? Pruned? How will they be replaced? How often will they need to be replaced? As someone who grows bonsai, I can tell you that stressed plants require constant attention ... it's not easy."

I know, I know, this is new territory. We're bound to make mistakes. The first tries are going to disappoint, I suppose, but look at these towers! They are man-bushes sitting in the middle of concrete jungles. They remind me of those "finger mountains" you see in China, surprising concentrations of plant life, like Limestone Ladies with Green Hair.

So if Tim De Chant wants to poo-poo buildings like these, let him. I think the rest of us should get out our hankies and wave at each and every tree being hauled up to the seventh floor, tenth floor, twentieth floor in Milan, and wish them well. They are pioneers, new neighbors being asked to live with us in the sky. They'll take in the CO2 and breathe out oxygen. We'll take in the oxygen and breathe out CO2. We'll water them. They'll aerate us. It's a whole new neighborhood. Yes, we may stumble as we rise, but rise we shall. These towers in Milan will lead the way. Pardon my boosterism, but every time I look at the images at the top of this page, I want shout "Yes!"